Semiconductor structures with field effect transistor(s) having low-resistance source/drain contact(s)

Abstract

Disclosed are semiconductor structures comprising a field effect transistor (FET) having a low-resistance source/drain contact and, optionally, low gate-to-source/drain contact capacitance. The structures comprise a semiconductor body and, contained therein, first and second source/drain regions and a channel region. A first gate is adjacent to the semiconductor body at the channel region and a second, non-functioning, gate is adjacent to the semiconductor body such that the second source/drain region is between the first and second gates. First and second source/drain contacts are on the first and source/drain regions, respectively. The second source/drain contact is wider than the first and, thus, has a lower resistance. Additionally, spacing of the first and second source/drain contacts relative to the first gate can be such that the first gate-to-second source/drain contact capacitance is equal to or less than the first gate-to-first source/drain contact capacitance. Also disclosed are associated formation methods.

What is claimed is: 
     
       1. A semiconductor structure comprising:
 a semiconductor body having a top surface and comprising: a first source/drain region; a second source/drain region; a channel region positioned laterally between said first source/drain region and said second source/drain region and a well region positioned laterally adjacent to said second source/drain region opposite said channel region and having a same type conductivity; 
 multiple gates comprising: a first gate adjacent to said top surface of said semiconductor body at said channel region and having a first sidewall; and a second gate adjacent to said top surface of said semiconductor body at said well region and having a second sidewall; 
 a gate sidewall spacer adjacent to the first sidewall; 
 dielectric material above said semiconductor body at said second source/drain region so as to be positioned laterally adjacent to and between said multiple gates, wherein said dielectric material is physically separated from said first sidewall by said gate sidewall spacer and immediately adjacent to said second sidewall; and 
 multiple contacts comprising: a first source/drain contact extending through said dielectric material and adjacent to said top surface of said semiconductor body at said first source/drain region; and, a second source/drain contact extending through said dielectric material adjacent to said top surface of said semiconductor body at said second source/drain region such that said second source/drain contact is positioned laterally between said first gate and said second gate, said second source/drain contact being wider than said first source/drain contact and closer to said second gate than said first gate. 
 
     
     
       2. The semiconductor structure of  claim 1 ,
 said second source/drain contact being separated from said first gate by a first distance and from said second gate by a second distance that is less than said first distance, and 
 said first source/drain contact being separated from said first gate by a third distance that is approximately equal to said first distance. 
 
     
     
       3. The semiconductor structure of  claim 1 ,
 said second source/drain contact being separated from said first gate by a first distance and from said second gate by a second distance that is less than said first distance, and 
 said first source/drain contact being separated from said first gate by a third distance that is less than said first distance. 
 
     
     
       4. The semiconductor structure of  claim 1 , said first gate being longer than said second gate. 
     
     
       5. The semiconductor structure of  claim 1 ,
 said first source/drain contact extending vertically through said dielectric material to said top surface of said semiconductor body at said first source/drain region and being essentially parallel to and physical separated from said first gate, and 
 said second source/drain contact extending vertically through said dielectric material to said top surface of said second source/drain contact and being essentially parallel to, physically separated from and positioned laterally between said first gate and said second gate. 
 
     
     
       6. A semiconductor structure comprising:
 a semiconductor body having a top surface and comprising: a first source/drain region; a second source/drain region; a channel region positioned laterally between said first source/drain region and said second source/drain region; and a well region positioned laterally adjacent to said second source/drain region opposite said channel region and having a same type conductivity as said channel region; 
 multiple gates comprising: a first gate adjacent to said top surface of said semiconductor body at said channel region; and a second gate adjacent to said top surface of said semiconductor body at said well region,
 said first gate having a first gate length and said second gate having a second gate length that is shorter than said first gate length, and 
 said second gate being non-functioning; 
 
 multiple contacts comprising: a first source/drain contact adjacent to said top surface of said semiconductor body at said first source/drain region; and, a second source/drain contact adjacent to said top surface of said semiconductor body at said second source/drain region such that said second source/drain contact is positioned laterally between said first gate and said second gate, said second source/drain contact being wider than said first source/drain contact and closer to said second gate than said first gate; and 
 dielectric material above said multiple gates and further above said semiconductor body at said first source/drain region and said second source/drain region so as to be positioned laterally adjacent to and between said multiple gates,
 said first source/drain contact extending vertically through said dielectric material to said top surface of said semiconductor body at said first source/drain region and being essentially parallel to and physical separated from said first gate, 
 said second source/drain contact extending vertically through said dielectric material to said top surface of said second source/drain contact and being essentially parallel to, physically separated from and positioned laterally between said first gate and said second gate, and 
 said first gate having a first sidewall, said second gate having a second sidewall, and said semiconductor structure further comprising a gate sidewall spacer immediately adjacent to said first sidewall, wherein said dielectric material is physically separated from said first sidewall by said gate sidewall spacer and immediately adjacent to said second sidewall. 
 
 
     
     
       7. The semiconductor structure of  claim 6 ,
 said second source/drain contact being separated from said first gate by a first distance and from said second gate by a second distance that is less than said first distance, and 
 said first source/drain contact being separated from said first gate by a third distance that is less than said first distance.